The present invention relates to a device for hydraulically actuating winches in a machine for laying pipes, such as pipes for oil and gas pipelines for example.
These machines are of the type comprising a motor unit provided with a side arm having one end hingeably connected to the motor unit itself. The side arm is therefore able to rotate with respect to the motor unit, being operated by a cable wound onto a winch rotatably mounted on the machine itself.
The side arm also comprises a cable extending along the whole length of the side arm itself. This cable is wound onto a winch coaxial with the winch for operation of the side arm and, at its free end, comprises a hook for fixing the pipes to be laid.
The winch operating the side arm and the winch operating the cable provided with a hook are actuated by hydraulic motors which are located inside the winches themselves and controlled by the operator via an oil-hydraulic circuit.
Adjustment of the movement of the hook and the side arm, in particular variation in the direction of rotation of the winches and stoppage of the winches, is performed by directly operating the respective hydraulic motors.
The pipe-laying machines must be able to work in series, namely the pipe is supported by several pipe-laying machines which operate in the vicinity of the zone where the pipe itself is laid.
In the event, for example, of the ground giving way, the load would be borne by only some of the pipe-laying machines and this situation could result in overturning of the pipe-laying machines which are still in operation.
Moreover, in the hydraulic actuating devices of the known type, the hydraulic pump functions constantly, irrespective of the required operation of the winches, with consequent overheating of the hydraulic oil and therefore restrictions on the use of the machine in particular in desert zones or zones where there are particularly high temperatures.